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Post by soupbone on Jan 30, 2018 9:08:53 GMT -7
I keep going back and forth and experimenting between a 5751 and 12ax7 in V1 and I can make them sound pretty much the same depending on how I tweak the controls. If I leave my tone and volume settings the same when I try each tube the tone, level of gain and volume are very different. However, with these settings the tone, gain and volume are pretty much identical..
12ax7: Vol 10 oclock, Tone 12 oclock
5751: Vol 1 oclock, Tone 1 oclock
So what exactly is happening inside the amp here? Am I putting more pressure on the power tubes when I use the 5751 and crank the amp? Will running the 5751 cranked shorten the life of the other tubes as compared to running the 12ax7 at lower volume?
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Deleted
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Post by Deleted on Jan 30, 2018 9:30:59 GMT -7
The 5751 has less gain than a 12AX7, so that's why you have to crank the volume a bit more to get it to sound the same. There's less gain being produced in the preamp.
5751's have a bit more headroom, and are a great way to get gain-y amps to play better with pedals.
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Post by soupbone on Jan 30, 2018 9:55:56 GMT -7
Yeah the 5751 obviously has less gain than the 12ax7. But if I am using them to the exact same end is one better than other for the health of the amp I guess is what I am asking.
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Deleted
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Post by Deleted on Jan 30, 2018 10:27:58 GMT -7
Neither is better or worse for the amp, it's just different. Sure, since the volume is a little higher you may be running the power tubes a little hotter, but isn't that the point?
I like getting as much gain out of the amp as possible, so 12AX7's usually do the trick for me.
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Post by premiumplus (Dave) on Jan 30, 2018 10:30:14 GMT -7
No, there's no more stress on the amp either way. You're just matching the gain that was hitting the output section by turning the volume up with the lower gain tube in there. If you were to put an oscilloscope or a good AC voltmeter on the grids of the output tubes you would see very close to the same voltage driving the output tubes whether the volume is turned down with a higher gain tube, or turned up with the lower gain one. It's six of one, half dozen of the other, basically. Just one guy's opinion, but I do believe you will see no difference regarding the health of your amp.
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Post by digs57 on Jan 30, 2018 10:47:22 GMT -7
JJ has a mid gain 12ax7 that was a nice compromise...
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